Efficiency spur gear set housing

Abstract

A hydraulic pump housing comprises passages formed in an inner wall separating the gear cavity and the pump cavity to allow for the movement of fluid into and out of the gear cavity, thereby alleviating some of the power loss caused by churning lubricating oil. The hydraulic pump may comprise spaces integrally formed in axially opposing surfaces of the gear cavity walls adjacent the area where the gears mesh to enable the churning oil to expand and flow around the gears.

We claim: 
     
       1. A housing for a spur gear set, the housing comprising a first member and a second member affixed together to define a gear cavity within which are located a drive gear and a driven gear submerged in fluid, the gear cavity having an area where the gears mesh, the first member comprising an inner wall forming a substantially planar rear inner surface of the gear cavity, the second member forming a substantially planar front inner surface of the gear cavity, the housing further comprising:
 a first expansion integrally formed in the rear inner surface of the inner wall adjacent to the area where the gears mesh, the first expansion being a space through which the fluid flows around the gears from one side of the area where the gears mesh to the other side of the area where the gears mesh; 
 a second expansion integrally formed in the front inner surface of the second member adjacent to the area where the gears mesh, the second expansion being a space through which the fluid flows around the gears from one side of the area where the gears mesh to the other side of the area where the gears mesh; 
 wherein the first expansion is defined by a first outwardly sloping wall located adjacent an area of highest oil pressure within the gear cavity and a second outwardly sloping wall located adjacent an area of lowest oil pressure within the gear cavity; and 
 wherein the second expansion is defined by a first outwardly sloping wall located adjacent an area of highest oil pressure within the gear cavity and a second outwardly sloping wall located adjacent an area of lowest oil pressure within the gear cavity. 
 
     
     
       2. The housing of  claim 1  wherein the first expansion and the second expansion are depressions. 
     
     
       3. The housing of  claim 1  wherein the first expansion and the second expansion are tunnels, each tunnel having an inlet opening adjacent to the area where the gears begin to mesh and an outlet opening adjacent to the area where the gears begin to unmesh. 
     
     
       4. The housing of  claim 1  wherein:
 the first expansion is defined by a first wall sloping outwardly away from the gears and a second wall sloping outwardly away from the gears, the first and second walls converging near the area of greatest engagement between where the drive gear and the driven gear mesh; and 
 the second expansion is defined by a first wall sloping outwardly away from the gears and a second wall sloping outwardly away from the gears, the first and second walls converging near the area of greatest engagement between where the drive gear and the driven gear mesh. 
 
     
     
       5. The housing of  claim 1  wherein:
 the first expansion comprises a concave area formed in the inner wall; and 
 the second expansion comprises a concave area formed in the front inner surface of the second member. 
 
     
     
       6. The housing of  claim 1  wherein:
 the first expansion comprises a first concave area formed in the inner wall, the first concave area being elongated in a direction defined by a line passing through an area of greatest gear engagement; and 
 the second expansion comprises a second concave area formed in the front inner surface, the second concave area being elongated in a direction defined by a line passing through an area of greatest gear engagement. 
 
     
     
       7. The housing of  claim 1  wherein the housing is part of a hydraulic pump, the first member is a housing body, and the second member is a flange. 
     
     
       8. The housing of  claim 1  further comprising one or more passages formed in the inner wall to allow movement of the fluid into and out of the gear cavity. 
     
     
       9. The housing of  claim 8  wherein the first member further comprises a perimeter wall forming a top inner surface, a bottom inner surface and side inner surfaces of the gear cavity, and wherein the one or more passages comprises two arcuate shaped side passages located near the side inner surfaces of the perimeter wall, each side passage forming an arc of less than ninety degrees. 
     
     
       10. The housing of  claim 9  wherein the side passages are equidistant from the top inner surface and the bottom inner surface of the perimeter wall. 
     
     
       11. The housing of  claim 10  wherein the first member comprises integrally formed top and bottom gear shrouds, the top gear shroud extending downward from the top inner surface of the perimeter wall and having downwardly converging curved sides that meet along a substantially linear apex located equidistant the gears, the bottom gear shroud extending upward from the bottom inner surface of the perimeter wall and having upwardly converging curved sides that meet along a substantially linear apex located equidistant the gears. 
     
     
       12. The housing of  claim 11  wherein the housing is part of a hydraulic pump, the first member is a housing body, and the second member is a flange. 
     
     
       13. A housing for a spur gear set, the housing comprising a first member and a second member affixed together to define a gear cavity within which are located a drive gear and a driven gear submerged in fluid, the gear cavity having an area where the gears mesh, the first member comprising an inner wall forming a substantially planar rear inner surface of the gear cavity, the second member forming a substantially planar front inner surface of the gear cavity, the housing further comprising:
 a first expansion integrally formed in the rear inner surface of the inner wall adjacent to the area where the gears mesh, the first expansion being a space through which the fluid flows around the gears from one side of the area where the gears mesh to the other side of the area where the gears mesh; 
 a second expansion integrally formed in the front inner surface of the second member adjacent to the area where the gears mesh, the second expansion being a space through which the fluid flows around the gears from one side of the area where the gears mesh to the other side of the area where the gears mesh; 
 wherein the first expansion comprises a first concave area formed in the inner wall, the first concave area being elongated in a direction defined by a line passing through an area of greatest gear engagement; and 
 wherein the second expansion comprises a second concave area formed in the front inner surface, the second concave area being elongated in a direction defined by a line passing through an area of greatest gear engagement. 
 
     
     
       14. The housing of  claim 13  wherein the first expansion and the second expansion are depressions. 
     
     
       15. The housing of  claim 13  wherein the first expansion and the second expansion are tunnels, each tunnel having an inlet opening adjacent to the area where the gears begin to mesh and an outlet opening adjacent to the area where the gears begin to unmesh. 
     
     
       16. The housing of  claim 13  wherein:
 the first expansion is defined by a first wall sloping outwardly away from the gears and a second wall sloping outwardly away from the gears, the first and second walls converging near the area of greatest engagement between where the drive gear and the driven gear mesh; and 
 the second expansion is defined by a first wall sloping outwardly away from the gears and a second wall sloping outwardly away from the gears, the first and second walls converging near the area of greatest engagement between where the drive gear and the driven gear mesh. 
 
     
     
       17. The housing of  claim 13  wherein:
 the first expansion is defined by a first outwardly sloping wall located adjacent an area of highest oil pressure within the gear cavity and a second outwardly sloping wall located adjacent an area of lowest oil pressure within the gear cavity; and 
 the second expansion is defined by a first outwardly sloping wall located adjacent an area of highest oil pressure within the gear cavity and a second outwardly sloping wall located adjacent an area of lowest oil pressure within the gear cavity. 
 
     
     
       18. The housing of  claim 13  wherein the housing is part of a hydraulic pump, the first member is a housing body, and the second member is a flange. 
     
     
       19. The housing of  claim 13  further comprising one or more passages formed in the inner wall to allow movement of the fluid into and out of the gear cavity. 
     
     
       20. The housing of  claim 19  wherein the first member further comprises a perimeter wall forming a top inner surface, a bottom inner surface and side inner surfaces of the gear cavity, and wherein the one or more passages comprises two arcuate shaped side passages located near the side inner surfaces of the perimeter wall, each side passage forming an arc of less than ninety degrees. 
     
     
       21. The housing of  claim 20  wherein the side passages are equidistant from the top inner surface and the bottom inner surface of the perimeter wall. 
     
     
       22. The housing of  claim 21  wherein the first member comprises integrally formed top and bottom gear shrouds, the top gear shroud extending downward from the top inner surface of the perimeter wall and having downwardly converging curved sides that meet along a substantially linear apex located equidistant the gears, the bottom gear shroud extending upward from the bottom inner surface of the perimeter wall and having upwardly converging curved sides that meet along a substantially linear apex located equidistant the gears. 
     
     
       23. The housing of  claim 22  wherein the housing is part of a hydraulic pump, the first member is a housing body, and the second member is a flange. 
     
     
       24. A housing for a spur gear set, the housing comprising a first member and a second member affixed together to define a gear cavity within which are located a drive gear and a driven gear submerged in fluid, the gear cavity having an area where the gears mesh, the first member comprising an inner wall forming a substantially planar rear inner surface of the gear cavity, the second member forming a substantially planar front inner surface of the gear cavity, the housing further comprising:
 a first expansion integrally formed in the rear inner surface of the inner wall adjacent to the area where the gears mesh, the first expansion being a space through which the fluid flows around the gears from one side of the area where the gears mesh to the other side of the area where the gears mesh; 
 a second expansion integrally formed in the front inner surface of the second member adjacent to the area where the gears mesh, the second expansion being a space through which the fluid flows around the gears from one side of the area where the gears mesh to the other side of the area where the gears mesh; 
 one or more passages formed in the inner wall to allow movement of the fluid into and out of the gear cavity; 
 wherein the first member further comprises a perimeter wall forming a top inner surface, a bottom inner surface and side inner surfaces of the gear cavity, and wherein the one or more passages comprises two arcuate shaped side passages located near the side inner surfaces of the perimeter wall, each side passage forming an arc of less than ninety degrees; 
 wherein the side passages are equidistant from the top inner surface and the bottom inner surface of the perimeter wall; and 
 wherein the first member comprises integrally formed top and bottom gear shrouds, the top gear shroud extending downward from the top inner surface of the perimeter wall and having downwardly converging curved sides that meet along a substantially linear apex located equidistant the gears, the bottom gear shroud extending upward from the bottom inner surface of the perimeter wall and having upwardly converging curved sides that meet along a substantially linear apex located equidistant the gears. 
 
     
     
       25. The housing of  claim 24  wherein the housing is part of a hydraulic pump, the first member is a housing body, and the second member is a flange.